In some arid regions of northern India, farmers have been defying the odds for centuries by raising melons and other moisture-loving crops where they were never meant to grow naturally. Indians have done this using a simple watering system that involves clay pots buried in the ground. These unglazed pots release water into the soil slowly, in effect forming little oases for the surrounding plants.
The system is ideal for areas where rainfall is unreliable and water too scarce to waste.
But recently, some Western gardeners in high rainfall areas have begun adapting the system, using plastic bottles, for liquid fertilizing - and, when needed, for watering too.
In India the farmers prepare the soil in the usual way, adding whatever amendments (manures, fertilizer, etc.) are deemed necessary - then digging a hole and burying the pot so that only the neck protrudes above the soil line. The pot is then filled with water and a stone or stopper is placed on top. The crops, usually deep-rooted vining plants, are then sown around the buried clay pot.
Because the pot is unglazed, water slowly seeps through the walls into the surrounding soil, where it nourishes the nearby plants. Water gets into the soil slowly and steadily, and none of it drains away before it can be used by the plant. Because the pot has a stone over the mouth, very little is lost through evaporation as well. The pots are filled up periodically.
After the technique became known in the West, not everyone who wanted to try it out could get hold of clay pots. So people improvised using plastic bottles and came up with a system that can be used as a liquid fertilizer as well as a water dispenser. Any size will do, but used milk jugs are ideal.
If you're interested, here's what to do:
Punch holes about knitting-needle size in the sides of the bottle or jug. Start at the base and punch the holes about two inches apart - half to all the way up depending on how deep you intend to set the bottle. Don't punch any holes in the bottom, as most of the water or fertilizer will drain straight down.
Now bury the bottle in the soil a fraction deeper than you have punched the holes. Some people like to bury the bottle so that it is barely seen. Others like much of it exposed, so that the air and sun can warm up the liquid.
After filling the bottle, screw the cap on loosely and check to see how quickly the water drains into the soil. If it is draining faster than you want, screw on the cap a little more tightly. If too slowly, loosen the cap some more. No liquid will drain from the bottle faster than air can get in to replace it. The loosening or tightening of the cap helps control the influx of air.